<PAGE>

                                                                     EXHIBIT 4.3

                           INVESTOR RIGHTS AGREEMENT
                                    BETWEEN
                             LSI LOGIC CORPORATION
                                      AND
                        LSI LOGIC STORAGE SYSTEMS, INC.
                                 MARCH 15, 2004
<PAGE>

                               TABLE OF CONTENTS

<Table>
<Caption>
                                                                      PAGE
                                                                      ----
<S>     <C>                                                           <C>
ARTICLE I  REGISTRATION RIGHTS......................................    1
 1.1    Requested Registration......................................    1
 1.2    Company Registration........................................    3
 1.3    Registration on Form S-3....................................    3
 1.4    Expenses of Registration....................................    3
 1.5    Registration Procedures.....................................    3
 1.6    Indemnification.............................................    4
 1.7    Information by LSI Logic....................................    6
 1.8    Rule 144 Reporting..........................................    6
 1.9    Limitations on Subsequent Registration Rights...............    6
1.10    Termination of Registration Rights..........................    6

ARTICLE II  RIGHT OF FIRST REFUSAL..................................    7
 2.1    Right of First Refusal to LSI Logic.........................    7

ARTICLE III  MISCELLANEOUS..........................................    8
 3.1    Limitation of Liability.....................................    8
 3.2    Entire Agreement............................................    8
 3.3    Governing Law...............................................    8
 3.4    Dispute Resolution..........................................    8
 3.5    Notices.....................................................    8
 3.6    Counterparts................................................    9
 3.7    Binding Effect; Assignment..................................    9
 3.8    Severability................................................    9
 3.9    Failure or Indulgence Not Waiver; Remedies Cumulative.......    9
3.10    Amendment...................................................    9
3.11    Interpretation..............................................    9
</Table>

                                        i
<PAGE>

<Table>
<Caption>
                                                                      PAGE
                                                                      ----
<S>     <C>                                                           <C>

ARTICLE IV  DEFINITIONS.............................................   10
 4.1    Ancillary Agreement.........................................   10
 4.2    Commission..................................................   10
 4.3    Common Stock................................................   10
 4.4    Dispute.....................................................   10
 4.5    Exchange Act................................................   10
 4.6    Indemnified Party...........................................   10
 4.7    Indemnifying Party..........................................   10
 4.8    Initial Public Offering.....................................   10
 4.9    LSI Logic Group.............................................   10
4.10    New Securities..............................................   10
4.11    Person......................................................   10
4.12    Registrable Securities......................................   10
4.13    Register, Registered and Registration.......................   10
4.14    Registration Expenses.......................................   10
4.15    Restricted Securities.......................................   10
4.16    Rule 144....................................................   10
4.17    Rule 145....................................................   11
4.18    Rule 415....................................................   11
4.19    Securities Act..............................................   11
4.20    Selling Expenses............................................   11
4.21    Separation Agreement........................................   11
4.22    SSI Group...................................................   11
</Table>

                                        ii
<PAGE>

                           INVESTOR RIGHTS AGREEMENT

     This Investor Rights Agreement (this "Agreement") is entered into as of
March 15, 2004, between LSI Logic Corporation, a Delaware corporation ("LSI
Logic"), and LSI Logic Storage Systems, Inc., a Delaware corporation ("SSI").
Capitalized terms used herein and not otherwise defined shall have the meanings
ascribed to such terms in Article IV hereof.

                                    RECITALS

     1.  LSI Logic and SSI entered into a Master Separation Agreement dated as
of December 31, 2003, as may be amended from time to time (the "Separation
Agreement") and other Ancillary Agreements to delineate and clarify their
relationship and further separate the businesses conducted by LSI Logic and SSI
(the "Separation").

     2.  In connection with the Separation, the parties intend that SSI grant to
LSI Logic certain rights, as provided for in this Agreement, with respect to the
registration of the shares of SSI capital stock held by LSI Logic and the right
of first refusal of LSI Logic to purchase certain securities of SSI.

     NOW, THEREFORE, in consideration of the foregoing and the covenants and
agreements set forth below, the parties hereto agree as follows:

                                   ARTICLE I

                              REGISTRATION RIGHTS

     1.1  Requested Registration.

     (a) Request for Registration.  Subject to the conditions set forth in this
Section 1.1, if SSI shall receive from LSI Logic a written request signed by an
authorized officer of LSI Logic that SSI effect the registration of all or any
portion of the Registrable Securities (which request shall state the number of
shares of Registrable Securities to be disposed of and the intended methods of
disposition of such shares by LSI Logic), SSI shall, as soon as practicable, use
its commercially reasonable efforts to effect such registration and to permit or
facilitate the sale and distribution of all or such portion of such Registrable
Securities as are specified in such request.

     (b) Limitations on Requested Registration.  SSI shall not be obligated to
effect, or to take any action to effect, any such registration pursuant to this
Section 1.1:

          (i) Prior to the time set forth in the applicable "lock up" provisions
     of the underwriting agreement executed by SSI and the underwriters in
     connection with SSI's Initial Public Offering;

          (ii) After the Company has initiated two such registrations pursuant
     to this Section 1.1 (counting for these purposes only registrations that
     have been declared or ordered effective and pursuant to which securities
     have been sold) in any twelve-month period; or

          (iii) If LSI Logic proposes to dispose of shares of Registrable
     Securities that may be immediately registered on Form S-3 pursuant to a
     request made under Section 1.3 hereof.

     (c) Deferral.  If (i) in the good faith judgment of the Board of Directors
of SSI, the filing of a registration statement covering the Registrable
Securities would be materially detrimental to SSI and the Board of Directors of
SSI concludes, as a result, that it is in the best interests of SSI to defer the
filing of such registration statement at such time, and (ii) SSI shall furnish
to LSI Logic a certificate signed by the Chairman of the Board of Directors of
SSI stating that in the good faith judgment of the Board of Directors of SSI, it
would be materially detrimental to SSI for such registration statement to be
filed in the near future and that it is, therefore, in the best interests of SSI
to defer the filing of such registration statement, then SSI shall have the
right to defer such filing for a period of not more than ninety (90) days after
receipt of the request of LSI Logic; provided, however, that SSI shall not defer
its obligation in this manner more than once in any twelve-month period.

                                        1
<PAGE>

     (d) Underwriting.  If LSI Logic intends to distribute the Registrable
Securities covered by its request by means of an underwriting, it shall so
advise SSI as a part of its request made pursuant to this Section 1.1. In such
event, the right of LSI Logic to include all or any portion of its Registrable
Securities in a registration pursuant to this Section 1.1 shall be conditioned
upon LSI Logic's participation in an underwriting and the inclusion of LSI
Logic's Registrable Securities to the extent provided herein. If SSI shall
request inclusion in any registration pursuant to Section 1.1 of securities
being sold for its own account, or if other persons shall request inclusion in
any registration pursuant to Section 1.1, LSI Logic may, in its sole discretion,
offer to include such securities in the underwriting and such offer shall be
conditioned upon the participation of SSI or such other persons in such
underwriting and the inclusion of SSI's and such person's other securities of
SSI and their acceptance of the further applicable provisions of this Section 1.
SSI shall (together with LSI Logic and other persons proposing to distribute
their securities through such underwriting) enter into an underwriting agreement
in customary form with the representative of the underwriter or underwriters
selected for such underwriting. LSI Logic and SSI shall jointly select the
underwriter or underwriters for such registration.

     Notwithstanding any other provision of this Section 1.1, if the
underwriters advise LSI Logic in writing that marketing factors require a
limitation on the number of shares to be underwritten, the number of Registrable
Securities that may be so included shall be allocated as follows: (i) first, to
LSI Logic; and (ii) second, to SSI, which SSI may allocate, at its discretion,
for its own account, or for the account of other holders or employees of SSI.

     If a person who has requested inclusion in such registration as provided
above does not agree to the terms of any such underwriting, such person shall be
excluded therefrom by written notice from SSI, the underwriter or LSI Logic. The
securities so excluded shall also be withdrawn from such registration. If shares
are so withdrawn from the registration and if the number of shares to be
included in such registration was previously reduced as a result of marketing
factors pursuant to this Section 1.1(d), then SSI shall offer to LSI Logic the
right to include additional Registrable Securities in the registration in an
aggregate amount equal to the number of shares so withdrawn, with such shares to
be allocated among LSI Logic or such other persons requesting additional
inclusion, in the manner set forth above.

     1.2  Company Registration.

     (a) Company Registration.  If SSI shall determine to register any of its
securities either for its own account or the account of a security holder or
holders, other than a registration pursuant to Section 1.1 or Section 1.3, a
registration relating solely to employee benefit plans, a registration relating
to the offer and sale of debt securities, a registration relating to a corporate
reorganization or other Rule 145 transaction, or a registration on any
registration form that does not permit secondary sales, SSI shall:

          (i) promptly give written notice of the proposed registration to LSI
     Logic; and

          (ii) use its commercially reasonable efforts to include in such
     registration (and any related qualification under state securities laws or
     other compliance), except as set forth in Section 1.2(b) below, and in any
     underwriting involved therein, all of such Registrable Securities as are
     specified in a written request or requests made by LSI Logic received by
     SSI within twenty (20) days after such written notice from SSI is mailed or
     delivered. Such written request may specify all or any portion of the
     Registrable Securities.

     (b) Underwriting.  If the registration of which SSI gives notice is for a
registered public offering involving an underwriting, SSI shall so advise LSI
Logic as a part of the written notice given pursuant to Section 1.2(a)(i). In
such event, the right of LSI Logic to registration pursuant to this Section 1.2
shall be conditioned upon LSI Logic's participation in such underwriting and the
inclusion of such LSI Logic's Registrable Securities in the underwriting to the
extent provided herein. If LSI Logic proposes to distribute its securities
through such underwriting it shall (together with SSI) enter into an
underwriting agreement in customary form with the representative of the
underwriter or underwriters selected by SSI, subject to LSI Logic's written
consent, which shall not be unreasonably withheld.

     Notwithstanding any other provision of this Section 1.2, if the
underwriters advise SSI in writing that marketing factors require a limitation
on the number of shares to be underwritten, the underwriters may

                                        2
<PAGE>

(subject to the limitations set forth below) limit the number of Registrable
Securities to be included in the registration and underwriting. SSI shall so
advise LSI Logic, and the number of shares of securities that are entitled to be
included in the registration and underwriting shall be allocated as follows: (i)
first, to SSI for securities being sold for its own account, and (ii) second, to
LSI Logic; and (iii) third, to any other holders of SSI securities.

     If a person who has requested inclusion in such registration as provided
above does not agree to the terms of any such underwriting, such person shall be
excluded therefrom by written notice from SSI or the underwriter. The securities
so excluded shall also be withdrawn from such registration. If shares are so
withdrawn from the registration and if the number of shares to be included in
such registration was previously reduced as a result of marketing factors
pursuant to Section 1.2(b), then SSI shall offer to LSI Logic the right to
include additional Registrable Securities in the registration in an aggregate
amount equal to the number of shares so withdrawn, with such shares to be
allocated among LSI Logic or such other persons requesting additional inclusion,
in the manner set forth above.

     (c) Right to Terminate Registration.  SSI shall have the right to terminate
or withdraw any registration initiated by it under this Section 1.2 prior to the
effectiveness of such registration whether or not LSI Logic has elected to
include securities in such registration.

     1.3  Registration on Form S-3.

     (a) Request for Form S-3 Registration.  After its Initial Public Offering,
SSI shall use its commercially reasonable efforts to qualify for registration on
Form S-3 or any comparable or successor form or forms. After SSI has qualified
for the use of Form S-3, in addition to the rights contained in the foregoing
provisions of this Section 1 and subject to the conditions set forth in this
Section 1.3, if SSI shall receive from LSI Logic a written request that SSI
effect any registration on Form S-3 or any similar short form registration
statement with respect to all or any portion of the Registrable Securities
(which request shall state the number of shares of Registrable Securities to be
disposed of and the intended methods of disposition of such shares by LSI
Logic), SSI shall use its commercially reasonable efforts to effect such
registration and to permit or facilitate the sale an distribution of all or such
portion of such Registrable Securities as are specified in such request.

     (b) Deferral.  The provisions of Section 1.1(c) shall apply to any
registration pursuant to this Section 1.3.

     (c) Underwriting.  If LSI Logic requests registration under this Section
1.3 intending to distribute the Registrable Securities covered by its request by
means of an underwriting, the provisions of Sections 1.1(d) shall apply to such
registration.

     1.4  Expenses of Registration.  All Registration Expenses incurred in
connection with registrations pursuant to Section 1.1, Section 1.2 and Section
1.3 hereof shall be borne by SSI; provided, however, that SSI shall not be
required to pay for any expenses of any registration proceeding begun pursuant
to Section 1.1 or Section 1.3 if the registration request is subsequently
withdrawn at the request of LSI Logic. All Selling Expenses relating to
securities registered on behalf of LSI Logic and any other holders of securities
shall be borne by LSI Logic and such other holders of securities included in
such registration pro rata among each other on the basis of the number of
Registrable Securities so registered.

     1.5  Registration Procedures.  In the case of each registration effected by
SSI pursuant to Section 1, SSI shall keep LSI Logic advised in writing as to the
initiation of each registration and as to the completion thereof. At its
expense, SSI shall use its commercially reasonable efforts to:

          (a) Keep such registration effective for a period of ending on the
     earlier of the date which is sixty (60) days from the effective date of the
     registration statement or such time as LSI Logic has completed the
     distribution described in the registration statement relating thereto;

          (b) Prepare and file with the Commission such amendments and
     supplements to such registration statement and the prospectus used in
     connection with such registration statement as may be necessary to comply
     with the provisions of the Securities Act with respect to the disposition
     of all securities covered by such registration statement for the period set
     forth in Section 1.5(a) above;

                                        3
<PAGE>

          (c) Furnish such number of prospectuses, including any preliminary
     prospectuses, and other documents incident thereto, including any amendment
     of or supplement to the prospectus, as LSI Logic from time to time may
     reasonably request;

          (d) Register and qualify the securities covered by such registration
     statement under such other securities laws of such jurisdiction as shall be
     reasonably requested by LSI Logic;

          (e) Notify each seller of Registrable Securities covered by such
     registration statement at any time when a prospectus relating thereto is
     required to be delivered under the Securities Act of the happening of any
     event as a result of which the prospectus included in such registration
     statement, as then in effect, includes an untrue statement of a material
     fact or omits to state a material fact required to be stated therein or
     necessary to make the statements therein not misleading or incomplete in
     light of the circumstances then existing, and following such notification
     promptly prepare and furnish to such seller a reasonable number of copies
     of a supplement to or an amendment of such prospectus as may be necessary
     so that, as thereafter delivered to the purchasers of such shares, such
     prospectus shall not include an untrue statement of a material fact or omit
     to state a material fact required to be stated therein or necessary to make
     the statements therein not misleading or incomplete in light of the
     circumstances then existing;

          (f) Furnish, on the date that such Registrable Securities are
     delivered to the underwriters for sale, if such securities are being sold
     through underwriters, (i) an opinion, dated as of such date, of the counsel
     representing SSI for the purposes of such registration, in form and
     substance as is customarily given to underwriters in an underwritten public
     offering, addressed to the underwriters, if any, and reasonably
     satisfactory to LSI Logic and (ii) a "comfort" letter dated as of such
     date, from the independent certified public accountants of SSI, in form and
     substance as is customarily given by independent certified public
     accountants to underwriters in an underwritten public offering, addressed
     to the underwriters;

          (g) Provide a transfer agent and registrar for all Registrable
     Securities registered pursuant to such registration statement and a CUSIP
     number for all such Registrable Securities, in each case not later than the
     effective date of such registration;

          (h) Comply with all applicable rules and regulations of the
     Commission, and make available to its security holders, as soon as
     reasonably practicable, an earnings statement covering the period of at
     least twelve months, but not more than eighteen months, beginning with the
     first month after the effective date of the Registration Statement, which
     earnings statement shall satisfy the provisions of Section 11(a) of the
     Securities Act;

          (i) Cause all such Registrable Securities registered pursuant
     hereunder to be listed on each securities exchange on which similar
     securities issued by SSI are then listed; and

          (j) In connection with any underwritten offering pursuant to a
     registration statement filed pursuant to Section 1.1 or Section 1.3 hereof,
     enter into an underwriting agreement in form reasonably necessary to effect
     the offer and sale of Common Stock; provided, however, that such
     underwriting agreement contains reasonable and customary provisions, and
     provided further, however, that LSI Logic shall also enter into and perform
     its obligations under such an agreement.

     1.6  Indemnification.

     (a) To the extent permitted by law, SSI will indemnify and hold harmless
LSI Logic, each of its officers, directors and partners, legal counsel, and
accountants and each person controlling LSI Logic within the meaning of Section
15 of the Securities Act, with respect to which registration, qualification, or
compliance has been effected pursuant to this Section 1, and each underwriter,
if any, and each person who controls within the meaning of Section 15 of the
Securities Act any underwriter, against all expenses, claims, losses, damages,
and liabilities (or actions, proceedings, or settlements in respect thereof)
arising out of or based on: (i) any untrue statement (or alleged untrue
statement) of a material fact contained or incorporated by reference in any
prospectus, offering circular, or other document (including any related
registration statement, notification, or the like) incident to any such
registration, qualification, or compliance, (ii) any omission (or alleged

                                        4
<PAGE>

omission) to state therein a material fact required to be stated therein or
necessary to make the statements therein not misleading, or (iii) any violation
(or alleged violation) by SSI of the Securities Act, any state securities laws
or any rule or regulation thereunder applicable to SSI and relating to action or
inaction required of SSI in connection with any offering covered by such
registration, qualification, or compliance, and SSI will reimburse LSI Logic,
each of its officers, directors, partners, legal counsel, and accountants and
each person controlling LSI Logic, each such underwriter, and each person who
controls any such underwriter, for any legal and any other expenses reasonably
incurred in connection with investigating and defending or settling any such
claim, loss, damage, liability, or action; provided, however, that SSI will not
be liable in any such case to the extent that any such claim, loss, damage,
liability, or action arises out of or is based on any untrue statement or
omission based upon written information furnished to SSI by LSI Logic, any of
LSI Logic's officers, directors, partners, legal counsel or accountants, any
person controlling LSI Logic, such underwriter or any person who controls any
such underwriter and stated to be specifically for use therein; and provided
further, however, that the indemnity agreement contained in this Section 1.6(a)
shall not apply to amounts paid in settlement of any such loss, claim, damage,
liability, or action if such settlement is effected without the consent of SSI
(which consent shall not be unreasonably withheld).

     (b) To the extent permitted by law, LSI Logic will, if Registrable
Securities held by LSI Logic are included in the securities as to which such
registration, qualification, or compliance is being effected, indemnify and hold
harmless SSI, each of its directors, officers, partners, legal counsel, and
accountants and each underwriter, if any, of SSI's securities covered by such a
registration statement, each person who controls SSI or such underwriter within
the meaning of Section 15 of the Securities Act, LSI Logic, and each of its
officers, directors, and partners, and each person controlling LSI Logic,
against all claims, losses, damages and liabilities (or actions in respect
thereof) arising out of or based on: (i) any untrue statement (or alleged untrue
statement) of a material fact contained or incorporated by reference in any such
registration statement, prospectus, offering circular, or other document, or
(ii) any omission (or alleged omission) to state therein a material fact
required to be stated therein or necessary to make the statements therein not
misleading, and will reimburse SSI and SSI's directors, officers, partners,
legal counsel, and accountants, persons, underwriters, or control persons for
any legal or any other expenses reasonably incurred in connection with
investigating or defending any such claim, loss, damage, liability, or action,
in each case to the extent, but only to the extent, that such untrue statement
(or alleged untrue statement) or omission (or alleged omission) is made in such
registration statement, prospectus, offering circular, or other document in
reliance upon and in conformity with written information furnished to SSI by LSI
Logic and stated to be specifically for use therein; provided, however, that the
obligations of LSI Logic hereunder shall not apply to amounts paid in settlement
of any such claims, losses, damages, or liabilities (or actions in respect
thereof) if such settlement is effected without the consent of LSI Logic (which
consent shall not be unreasonably withheld); and provided further, however, that
in no event shall any indemnity under this Section 1.6 exceed the net proceeds
from the offering received by LSI Logic.

     (c) Each party entitled to indemnification under this Section 1.6 (the
"Indemnified Party") shall give notice to the party required to provide
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of such claim or any
litigation resulting therefrom; provided, however, that counsel for the
Indemnifying Party, who shall conduct the defense of such claim or any
litigation resulting therefrom, shall be approved by the Indemnified Party
(whose approval shall not be unreasonably withheld), and the Indemnified Party
may participate in such defense at such party's expense; and provided further,
however, that the failure of any Indemnified Party to give notice as provided
herein shall not relieve the Indemnifying Party of its obligations under this
Section 1.6, to the extent such failure is not prejudicial. No Indemnifying
Party, in the defense of any such claim or litigation, shall, except with the
consent of each Indemnified Party, consent to entry of any judgment or enter
into any settlement that does not include as an unconditional term thereof the
giving by the claimant or plaintiff to such Indemnified Party of a release from
all liability in respect to such claim or litigation. Each Indemnified Party
shall furnish such information regarding itself or the claim in question as an
Indemnifying Party may reasonably request in writing and as shall be reasonably
required in connection with defense of such claim and litigation resulting
therefrom.

                                        5
<PAGE>

     (d) If the indemnification provided for in this Section 1.6 is held by a
court of competent jurisdiction to be unavailable to an Indemnified Party with
respect to any loss, liability, claim, damage, or expense referred to herein,
then the Indemnifying Party, in lieu of indemnifying such Indemnified Party
hereunder, shall contribute to the amount paid or payable by such Indemnified
Party as a result of such loss, liability, claim, damage, or expense in such
proportion as is appropriate to reflect the relative fault of the Indemnifying
Party on the one hand and of the Indemnified Party on the other in connection
with the statements or omissions that resulted in such loss, liability, claim,
damage, or expense as well as any other relevant equitable considerations. The
relative fault of the Indemnifying Party and of the Indemnified Party shall be
determined by reference to, among other things, whether the untrue or alleged
untrue statement of a material fact or the omission to state a material fact
relates to information supplied by the Indemnifying Party or by the Indemnified
Party and the parties' relative intent, knowledge, access to information, and
opportunity to correct or prevent such statement or omission.

     (e) Notwithstanding the foregoing, to the extent that the provisions on
indemnification and contribution contained in the underwriting agreement entered
into in connection with the underwritten public offering are in conflict with
the foregoing provisions, the provisions in the underwriting agreement shall
control.

     1.7  Information by LSI Logic.  LSI Logic shall furnish to SSI such
information regarding LSI Logic and the distribution proposed by LSI Logic as
SSI may reasonably request in writing and as shall be reasonably required in
connection with any registration, qualification, or compliance referred to in
this Section 1.

     1.8  Rule 144 Reporting.  With a view to making available the benefits of
certain rules and regulations of the Commission that may permit the sale of the
Restricted Securities to the public without registration, SSI agrees to use its
best efforts to:

          (a) Make and keep public information regarding SSI available as those
     terms are understood and defined in Rule 144 under the Securities Act, at
     all times from and after ninety (90) days following the effective date of
     the first registration under the Securities Act filed by SSI for an
     offering of its securities to the general public;

          (b) File with the Commission in a timely manner all reports and other
     documents required of SSI under the Securities Act and the Exchange Act at
     any time after it has become subject to such reporting requirements; and

     So long as LSI Logic owns any Restricted Securities, furnish to LSI Logic
forthwith upon written request a written statement by SSI as to its compliance
with the reporting requirements of Rule 144 (at any time from and after ninety
(90) days following the effective date of the first registration statement filed
by SSI for an offering of its securities to the general public), and of the
Securities Act and the Exchange Act (at any time after it has become subject to
such reporting requirements), a copy of the most recent annual or quarterly
report of SSI, and such other reports and documents so filed as LSI Logic may
reasonably request in availing itself of any rule or regulation of the
Commission allowing LSI Logic to sell any such securities without registration.

     1.9  Limitations on Subsequent Registration Rights.  From and after the
date of this Agreement, SSI shall not, without the prior written consent of a
LSI Logic, enter into any agreement with any holder or prospective holder of any
securities of SSI giving such holder or prospective holder any registration
rights the terms of which are pari passu with or senior to the registration
rights granted to LSI Logic hereunder.

     1.10  Termination of Registration Rights.  The right of LSI Logic to
request registration or inclusion in any registration pursuant to Section 1.1,
Section 1.2 or Section 1.3 and the limitations on SSI with respect to the
granting of subsequent registration rights pursuant to Section 1.9 shall
terminate on the earlier of (i) such date, on or after the closing of the
Company's Initial Public Offering, on which all shares of Registrable Securities
held or entitled to be held upon conversion by LSI Logic may immediately be sold
under Rule 144 during any ninety (90)-day period, and (ii) three (3) years after
the closing of SSI's Initial Public Offering.

                                        6
<PAGE>

                                   ARTICLE II

                             RIGHT OF FIRST REFUSAL

     2.1  Right of First Refusal to LSI Logic.  SSI hereby grants to LSI Logic
(subject to subsequent adjustments for stock splits, stock dividends, reverse
stock splits and the like), the right of first refusal to purchase its pro rata
share of New Securities (as defined in Section 2.1(a)) that SSI may, from time
to time, propose to sell and issue after the date of this Agreement. LSI Logic's
pro rata share, for purposes of this right of first refusal, is equal to the
ratio of (a) the number of shares of Common Stock owned by LSI Logic immediately
prior to the issuance of New Securities (assuming exercise of all outstanding
convertible securities, rights, options and warrants, directly or indirectly,
into Common Stock held by LSI Logic) to (b) the total number of shares of Common
Stock outstanding immediately prior to the issuance of New Securities (assuming
exercise of all outstanding convertible securities, rights, options and
warrants, directly or indirectly, held by all of holders of all of SSI's
securities.

     (a) "New Securities" shall mean any capital stock (including Common Stock
and/or Preferred Stock) of SSI whether now authorized or not, and rights,
convertible securities, options or warrants to purchase such capital stock, and
securities of any type whatsoever that are, or may become, exercisable or
convertible into capital stock; provided, however, that the term "New
Securities" does not include:

          (i) securities issued or issuable to officers, employees, directors,
     consultants, placement agents, and other service providers of SSI (or any
     subsidiary) pursuant to stock grants, option plans, purchase plans,
     agreements or other employee stock incentive programs or arrangements
     approved by the Board of Directors of SSI;

          (ii) securities issued pursuant to the conversion or exercise of any
     outstanding convertible or exercisable securities as of this date of this
     Agreement;

          (iii) securities offered pursuant to SSI's Initial Public Offering;

          (iv) securities issued or issuable pursuant to the acquisition of
     another corporation by SSI by merger, purchase of substantially all of the
     assets or other reorganization or to a joint venture agreement, provided,
     that such issuances are approved by the Board of Directors of SSI;

          (v) securities issued or issuable to banks, equipment lessors or other
     financial institutions pursuant to a commercial leasing or debt financing
     transaction approved by the Board of Directors of SSI;

          (vi) securities issued or issuable in connection with sponsored
     research, collaboration, technology license, development, OEM, marketing or
     other similar agreements or strategic partnerships approved by the Board of
     Directors of SSI;

          (vii) securities issued to suppliers or third party service providers
     in connection with the provision of goods or services pursuant to
     transactions approved by the Board of Directors of SSI;

          (viii) securities of SSI which are otherwise excluded by the
     affirmative unanimous vote of the Board of Directors of SSI; and

          (ix) any right, option or warrant to acquire any security convertible
     into the securities excluded from the definition of New Securities pursuant
     to Section 2.1(a)(i) through Section 2.1(a)(viii) above.

     (b) In the event SSI proposes to undertake an issuance of New Securities,
it shall give LSI Logic written notice of its intention, describing the type of
New Securities, and their price and the general terms upon which SSI proposes to
issue the same. LSI Logic shall have twenty (20) days after any such notice is
mailed or delivered to agree to purchase LSI Logic's pro rata share of such New
Securities for the price and upon the terms specified in the notice by giving
written notice to SSI and stating therein the quantity of New Securities to be
purchased.

     (c) In the event LSI Logic fails to exercise fully the right of first
refusal within said twenty (20) day period (the "Election Period"), SSI shall
have sixty (60) days thereafter to sell or enter into an agreement (pursuant to
which the sale of New Securities covered thereby shall be closed, if at all,
within sixty (60) days

                                        7
<PAGE>

from the date of said agreement) to sell that portion of the New Securities with
respect to which LSI Logic's right of first refusal option set forth in this
Section 2.1 was not exercised, at a price and upon terms no more favorable to
the purchasers thereof than specified in SSI's notice to LSI Logic delivered
pursuant to Section 2.1(b). In the event SSI has not sold within such sixty (60)
day period following the Election Period, or such sixty (60) day period
following the date of said agreement, SSI shall not thereafter issue or sell any
New Securities, without first again offering such securities to LSI Logic in the
manner provided in this Section 2.1.

     (d) The right of first refusal granted under this Agreement shall expire
upon the earlier of (i) three (3) years after the Initial Public Offering and
(ii) the distribution by LSI Logic to the holders of its common stock, by means
of a pro rata distribution, of shares of SSI Common Stock then owned by LSI
Logic in a transaction intended to qualify as a tax-free distribution under
section 355 of the Internal Revenue Code of 1986, as amended.

                                  ARTICLE III

                                 MISCELLANEOUS

     3.1  Limitation of Liability.  IN NO EVENT SHALL ANY MEMBER OF THE LSI
LOGIC GROUP OR SSI GROUP BE LIABLE TO ANY OTHER MEMBER OF THE LSI LOGIC GROUP OR
SSI GROUP FOR ANY SPECIAL, CONSEQUENTIAL, INDIRECT, INCIDENTAL OR PUNITIVE
DAMAGES OR LOST PROFITS, HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY
(INCLUDING NEGLIGENCE) ARISING IN ANY WAY OUT OF THIS AGREEMENT, WHETHER OR NOT
SUCH PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES; PROVIDED,
HOWEVER, THAT THE FOREGOING LIMITATIONS SHALL NOT LIMIT EITHER PARTY'S
INDEMNIFICATION OBLIGATIONS FOR LIABILITIES AS SET FORTH IN SECTION 1.6 HEREOF
OR IN THE INDEMNIFICATION AND INSURANCE MATTERS AGREEMENT.

     3.2  Entire Agreement.  This Agreement, the Separation Agreement, the other
Ancillary Agreements and the exhibits and schedules referenced or attached
hereto and thereto, constitute the entire agreement between the parties with
respect to the subject matter hereof and thereof and shall supersede all prior
written and oral and all contemporaneous oral agreements and understandings with
respect to the subject matter hereof and thereof.

     3.3  Governing Law.  This Agreement shall be construed in accordance with,
and all Disputes hereunder shall be governed by, the laws of the State of
California, excluding its conflict of law rules and the United Nations
Convention on Contracts for the International Sale of Goods. The Superior Court
of Santa Clara County and/or the United States District Court for the Northern
District of California shall have jurisdiction and venue over all Disputes
between the parties that are permitted to be brought in a court of law pursuant
to Section 3.4 below.

     3.4  Dispute Resolution.  Any Disputes under this Agreement shall be
addressed using the same procedure set forth in the Separation Agreement.

     3.5  Notices.  Notices, offers, requests or other communications required
or permitted to be given by either party pursuant to the terms of this Agreement
shall be given in writing to the respective parties at the following addresses:

     if to LSI Logic:

     LSI Logic Corporation
     1621 Barber Lane
     Milpitas, CA 95035
     Attention: General Counsel
     Fax: (408) 433-6896

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<PAGE>

     if to SSI:

     LSI Logic Storage Systems, Inc.
     1621 Barber Lane
     Milpitas, CA 95035
     Attention: General Counsel
     Fax: (408) 433-8323

or to such other address as the party to whom notice is given may have
previously furnished to the other in writing as provided herein. Any notice
involving non-performance, termination, or renewal shall be sent by hand
delivery, recognized overnight courier or, within the United States, may also be
sent via certified mail, return receipt requested. All other notices may also be
sent by fax, confirmed by first class mail. All notices shall be deemed to have
been given and received on the earlier of actual delivery or three (3) days from
the date of postmark.

     3.6  Counterparts.  This Agreement, including the exhibits and schedules
hereto, may be executed in counterparts, each of which shall be deemed to be an
original but all of which shall constitute one and the same agreement.

     3.7  Binding Effect; Assignment.  This Agreement shall inure to the benefit
of and be binding upon the parties hereto and their respective legal
representatives and successors in interest, and nothing in this Agreement,
express or implied, is intended to confer upon any other Person any rights or
remedies of any nature whatsoever under or by reason of this Agreement. This
Agreement may be enforced separately by each member of the LSI Logic Group and
each member of the SSI Group. Neither party may assign this Agreement or any
rights or obligations hereunder, without the prior written consent of the other
party, and any such assignment shall be void. Any permitted assignee shall agree
to perform the obligations of the assignor of this Agreement, and this Agreement
shall inure to the benefit of and be binding upon any permitted assignee.

     3.8  Severability.  If any term or other provision of this Agreement or the
exhibits or schedules attached hereto is determined by a nonappealable decision
by a court, administrative agency or arbitrator to be invalid, illegal or
incapable of being enforced by any rule of law or public policy, all other
conditions and provisions of this Agreement shall nevertheless remain in full
force and effect so long as the economic or legal substance of the transactions
contemplated hereby is not affected in any manner materially adverse to either
party. Upon such determination that any term or other provision is invalid,
illegal or incapable of being enforced, the parties hereto shall negotiate in
good faith to modify this Agreement so as to effect the original intent of the
parties as closely as possible in an acceptable manner to the end that
transactions contemplated hereby are fulfilled to the fullest extent possible.

     3.9  Failure or Indulgence Not Waiver; Remedies Cumulative.  No failure or
delay on the part of either party hereto in the exercise of any right hereunder
shall impair such right or be construed to be a waiver of, or acquiescence in,
any breach of any representation, warranty or agreement herein, nor shall any
single or partial exercise or waiver of any such right preclude other or further
exercise thereof or of any other right. All rights and remedies existing under
this Agreement or the exhibits or schedules attached hereto are cumulative to,
and not exclusive of, any rights or remedies otherwise available.

     3.10  Amendment.  No change or amendment shall be made to this Agreement or
the exhibits or schedules attached hereto except by an instrument in writing
signed on behalf of each of the parties to such agreement.

     3.11  Interpretation.  The headings contained in this Agreement, in any
exhibit or schedule attached hereto and in the table of contents to this
Agreement are for reference purposes only and shall not affect in any way the
meaning or interpretation of this Agreement. Any capitalized term used in any
exhibit or schedule but not otherwise defined therein, shall have the meaning
assigned to such term in this Agreement. When a reference is made in this
Agreement to an article, section, exhibit or schedule, such reference shall be
to an article or section of, or an exhibit or schedule to, this Agreement,
unless otherwise indicated.

                                        9
<PAGE>

                                   ARTICLE IV

                                  DEFINITIONS

     4.1  Ancillary Agreement.  "Ancillary Agreement" has the meaning set forth
in the Separation Agreement.

     4.2  Commission.  "Commission" shall mean the Securities and Exchange
Commission or any other federal agency at the time administering the Securities
Act.

     4.3  Common Stock.  "Common Stock" means the common stock of SSI, including
any and all classes of such common stock.

     4.4  Dispute.  "Dispute" has the meaning set forth in the Separation
Agreement.

     4.5  Exchange Act.  "Exchange Act" shall mean the Securities Exchange Act
of 1934, as amended, or any similar successor federal statute and the rules and
regulations thereunder, all as the same shall be in effect from time to time.

     4.6  Indemnified Party.  "Indemnified Party" shall have the meaning set
forth in Section 1.6(c) hereto.

     4.7  Indemnifying Party.  "Indemnifying Party" shall have the meaning set
forth in Section 1.6(c) hereto.

     4.8  Initial Public Offering.  "Initial Public Offering" shall mean the
closing of the SSI's first firm commitment underwritten public offering of the
SSI's Class A Common Stock registered under the Securities Act.

     4.9  LSI Logic Group. "LSI Logic Group" has the meaning set forth in the
Separation Agreement.

     4.10  New Securities.  "New Securities" shall have the meaning set forth in
Section 2.1(a) hereto.

     4.11  Person.  "Person" has the meaning set forth in the Separation
Agreement.

     4.12  Registrable Securities.  "Registrable Securities" shall mean (i) any
and all shares of Common Stock and (ii) any Common Stock issued as a dividend or
other distribution with respect to or in exchange for or in replacement of the
shares referenced in (i) above; provided, however, that Registrable Securities
shall not include any shares of Common Stock described in clause (i) or (ii)
above which have previously been registered or which have been sold to the
public either pursuant to a registration statement or Rule 144, or which have
been sold in a private transaction in which the transferor's rights under this
Agreement are not validly assigned in accordance with this Agreement.

     4.13  Register, Registered and Registration.  The terms "register,"
"registered" and "registration" shall refer to a registration effected by
preparing and filing a registration statement in compliance with the Securities
Act and applicable rules and regulations thereunder, and the declaration or
ordering of the effectiveness of such registration statement.

     4.14  Registration Expenses.  "Registration Expenses" shall mean all
expenses incurred in effecting any registration pursuant to this Agreement,
including, without limitation, all registration, qualification, and filing fees,
printing expenses, escrow fees, fees and disbursements of counsel for SSI and
one special counsel for LSI Logic, state securities law fees and expenses, and
expenses of any regular or special audits incident to or required by any such
registration, but shall not include Selling Expenses, fees and disbursements of
other counsel for LSI Logic and the compensation of regular employees of SSI,
which shall be paid in any event by SSI.

     4.15  Restricted Securities.  "Restricted Securities" shall mean any
Registrable Securities that have not been registered under the Securities Act.

     4.16  Rule 144.  "Rule 144" shall mean Rule 144 as promulgated by the
Commission under the Securities Act, as such Rule may be amended from time to
time, or any similar successor rule that may be promulgated by the Commission.

                                        10
<PAGE>

     4.17  Rule 145.  "Rule 145" shall mean Rule 145 as promulgated by the
Commission under the Securities Act, as such Rule may be amended from time to
time, or any similar successor rule that may be promulgated by the Commission

     4.18  Rule 415.  "Rule 415" shall mean Rule 415 as promulgated by the
Commission under the Securities Act, as such Rule may be amended from time to
time, or any similar successor rule that may be promulgated by the Commission.

     4.19  Securities Act.  "Securities Act" shall mean the Securities Act of
1933, as amended, or any similar successor federal statute and the rules and
regulations thereunder, all as the same shall be in effect from time to time.

     4.20  Selling Expenses.  "Selling Expenses" shall mean all underwriting
discounts, selling commissions and stock transfer taxes applicable to the sale
of Registrable Securities and fees and disbursements of counsel for LSI Logic
(other than the fees and disbursements of one special counsel to LSI Logic
included in Registration Expenses).

     4.21  Separation Agreement.  "Separation Agreement" has the meaning set
forth in the Recitals hereof.

     4.22  SSI Group. "SSI Group" has the meaning set forth in the Separation
Agreement.

                  [Remainder of Page Intentionally Left Blank]

                                        11
<PAGE>

     IN WITNESS WHEREOF, the parties have signed this Investor Rights Agreement
effective as of the date first set forth above.

<Table>
<S>                                            <C>
LSI LOGIC CORPORATION                          LSI LOGIC STORAGE SYSTEMS, INC.


By: /s/ WILFRED J. CORRIGAN                    By: /s/ THOMAS GEORGENS
-------------------------                      -------------------------


Name: Wilfred J. Corrigan                      Name: Thomas Georgens
-------------------------                      -------------------------

Title: Chairman/CEO                            Title: President
-------------------------                      -------------------------
</Table>

                 [SIGNATURE PAGE TO INVESTOR RIGHTS AGREEMENT]

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